The instant invention relates to a hysteresis coupling having a magnetic cylinder made of a permanent magnetic material and a thrust ring made of a hysteresis material. The thrust ring is connected to a thrust ring holder and separated from the magnetic cylinder by an air gap.
Hysteresis couplings can be used, for example, to limit the torque in a drive and to actuate actuating drives used for rotary valves and ventilation flaps, etc.
A hysteresis coupling equipped with a magnetic cylinder and a thrust ring separated from the magnetic cylinder by an air gap is known from CH PS 664052. This patent discloses how to operate and size the parts of a hysteresis coupling for a predetermined torque. At high rotational speeds the disclosed hysteresis coupling produces a noise which is often annoying when used in a residential area.